Underwater blast behaviors of enhanced lattice truss sandwich panels

In this paper the enhanced lattice topology (defined as hourglass), with the improved resistance to tearing of face sheets, is used to improve the underwater blast impact performance of lattice truss structures. The stainless-steel lattices are fabricated by an interlocking and vacuum brazing method, all with a core relative density of about 4%. Their mechanical behaviors are investigated under quasi-static out-of-plane compression and underwater blast impact, in the latter case using an underwater shock simulator. Results show that the quasi-static compressive strength of the hourglass lattice is similar to that of the pyramidal lattice for the relative density chosen in this paper. The failure modes of the hourglass lattice panels subjected to underwater blast impact consist of core truss buckling, node imprinting and stretching of the front face sheets. The obtained results confirm that the hourglass lattice sandwich panel shows an approximately 60% reduction in the maximum panel deflection with respect to a monolithic plate of equal mass per unit area. Furthermore, the underwater blast impact performance of the hourglass lattice panels outperforms that of the pyramidal lattice panels of equal weight per unit area in the sense of resistance to stretching and tearing of the face sheets. Therefore, sandwich structure with the hourglass lattice design is a potential candidate for protective structures.